1. Field of the invention
The field of the invention relates to a connector having a receptacle portion for receiving a male member such as a pin contact.
2. Brief Description of the Prior Art
Electrical connectors for mating with a plurality of square posts or pins are well known in the electronics field. Referring to FIG. 1, a contact of one such prior art connector assembly is shown including a pin or plug type contact 2 which may be inserted within a female contact 4. A pair of upper transversely extending spring members 6 and 8 are arranged on the upper side of the contact to provide a resilient force in the downward direction upon a pin inserted therein. An elongated member 10 which is bent inwardly into the contact body in the longitudinal direction thereof is arranged on the lower surface of the contact. While the inner width of the body is dimensioned such that the square pin contact 2 fits therein, the height of the inner side (i.e. the distance between the inner surface of members 6,8 and the upper surface of the elongated member 10) is made smaller than one side thereof. As a result, when the pin contact is inserted into the receptacle portion of the contact body, the spring members 6,8 apply a downwardly resilient force thereon and the contact pressure is controlled by the elongated member. When the contact is made from a conventional metal such as brass or phosphoric bronze rather than a precious metal such as gold or platinum, and is employed in a low voltage circuit, vibrations or shocks can create serious problems in the electrical connection between the female contacts and square pins positioned therein.
Although the contact surfaces of a connector are generally covered by a thin film of oil used in the manufacturing process and/or a thin oxide layer formed by a natural oxidation of the metal, the insertion type connector forms a conductive contact by means of a wiping action which breaks the oil film or the oxide layer by contact pressure at the time the pin is inserted into the receptacle. Even if a thin oil film or oxide layer exists between the contact points, an electrical connection is established by a tunnelling effect or a fretting action which breaks through it due to the applied voltage.
If the connector or contact portions are used for a substantial period of time in a vibrationary environment, the electrical connections will deteriorate. Regardless of contact types such as a plane contact, line contact, or point contact, the metal or plated surface of the contact is quite irregular when viewed microscopically. Thus, when a pin and a receptacle are connected to each other, conduction is possible by means of metallic fusion or similar connections of many contact points between the pin and the receptacle. The contact portions "cleaned" by the wiping action, however, are oxidized promptly thereby forming an insulating layer on the surfaces thereof. When the contact points are disturbed due to vibrations, new contact points are created due to the action described above, while the former contact points are oxidized and promptly form an oxide layer as explained above. Thus, when the shifting of the contacts repeatedly occurs, the oxide portions build rapidly to produce a black powdered oxide material which finally results in non-conductivity.
In order to avoid the problems set forth above, means may be employed for inhibiting relative movement between the pin and receptacle and for maintaining an air tight connection therebetween. However, an increased contact pressure or an increased contact area results in difficulty of insertion of withdrawal. In addition, increased contact pressure increases abrasion of the plated surfaces of the connector. Where a mass termination type connector is employed, the pressure exerted upon each pin is preferably made as small as possible to facilitate insertion or withdrawal. Further, the contact pressure should not be excessive to avoid damaging the locking tabs engaging the contacts in the insulator when the male connector is pulled out. Still further, in case a "wrenching" occurs wherein a pin contact is inserted or withdrawn at an angle from the connector, the elongated member (tongue member) may be deflected beyond its elastic limit resulting in permanent deformation of the curved portion thereof.